Investigations of interactions between nucleoside transporters and adenosine receptors in three cell models

Abstract

Adenosine is a modulator that is involved in a large number of physiological processes in peripheral nerves, tissues and in the CNS. Adenosine levels are regulated by the intracellular and extracellular adenosine metabolizing enzymes as well as two main classes of nucleoside transporters, sodium-dependent and sodium-independent, which catalyze the movement of nucleosides across biological membranes. Once formed, adenosine can act on cell surface adenosine receptors. These studies were performed to (1) determine whether sodium-dependent transporters can function in the release of nucleosides during conditions that disturb metabolic or ionic homeostasis; (2) determine whether nucleoside release by sodium-independent (es) transporters can be differentially regulated by adenosine receptor stimulation; and (3) characterize the inhibitory effects of propentofylline on cAMP phosphodiesterase, adenosine transporters and three adenosine receptor types. These studies characterized several of the roles that specific transporters may play in regulating adenosine levels, and thus, the receptor-mediated effects of adenosine. (Abstract shortened by UMI.)